Given a binary tree, return the postorder traversal of its nodes' values.
Example:
Input: [1,null,2,3]
1
\
2
/
3
Output: [3,2,1]
Follow up: Recursive solution is trivial, could you do it iteratively?
这个和leetcode144类似,是利用递归求后序遍历。
python代码:
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def postorderTraversal(self, root: TreeNode) -> List[int]:
nums = []
if not root:
return nums
nums.extend(self.postorderTraversal(root.left))
nums.extend(self.postorderTraversal(root.right))
nums.append(root.val)
return nums
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